The present invention relates to a digitizer and, more particularly, but not exclusively to a digitizer for accepting user input to a computing device.
Input devices typically use one of three most popular technologies, movement tracking, as in a mouse, rollerball and like devices, touch technology as in a touch screen and pointing systems as with a stylus. Different applications may be most suited to certain input technologies or systems.
Touch technologies are commonly used as input devices for a variety of products. The use of touch digitizers is growing rapidly due to the emergence of new mobile devices, such as web pads, web tablets, Tabletxe2x80x94PC, wireless screens and hand-held computers. Such new mobile devices usually come without any integrated keyboard or mouse, due to mobility considerations, and therefore frequently use touch input devices. As well as mobile devices, touch digitizers are useful in computer systems offering services to the general public in shops and the like, where mice are likely to be broken or removed, and are also useful for computers to be used in hazardous environments such as factory floors, since they allow the computer to be suitably sealed.
To date, touch sensitive displays have been implemented using a variety of technologies for detecting touch stimuli. In one example, a transparent overlay is placed over a display. The overlay contains an array of sensors that can be resistive, conductive or capacitive. The sensors are arranged in rows and columns spanning the display screen area; and each sensor is therefore indicative of a particular touch location. Another technology involves the processing of an optical signal scanned across a CRT screen in order to determine a touch location. Yet another technology involves an array of force sensitive transducers that are mounted around the periphery of a display. Each transducer generates a different signal upon receiving a touch stimulus. The relative magnitudes of these signals can then be used to determine a touch location. The major drawback of these technologies and others is that they are all targeted at identifying the location of a single input (e.g. a stylus, a finger). None of these solutions supports multiple inputs simultaneously.
With the emergence of Internet appliances such as Tablet PCs, the need for using a computer keyboard has become evident. Since connecting a standard keyboard to the Tablet PC diminishes the mobility of the device, the requirement to feed these devices with alphanumeric information is usually accomplished by the implementation of an xe2x80x9con-screenxe2x80x9d keyboard. An xe2x80x9con-screenxe2x80x9d keyboard is a scheme of a computer keyboard graphically illustrated on the display. Inputs are provided by successively touching the relevant graphical keys using a finger or a stylus. However, due to the inherent structure of existing touch technologies, it is impossible to support more than one touch (i.e. one key) at a time. This inherent property makes it impossible to apply the kind of convenient and intuitive keyboard operation known as xe2x80x9cchord keyxe2x80x9d, for example xe2x80x9cShiftxe2x80x9d+xe2x80x9cLetterxe2x80x9d or xe2x80x9ccontrolxe2x80x9d+xe2x80x9caltxe2x80x9d+xe2x80x9cdeletexe2x80x9d, at the same time.
There had been attempts in the past to combine touch sensitive input devices with other kinds of digitizer. U.S. Pat. No. 4,686,332 by Grenians, describes a combination of a capacitance finger sensible sensor with an electromagnetic stylus, both incorporated in the same transparent foil. In Grenians, the same conductors are used for measuring capacitance and for transmitting the electromagnetic signal to the pick-up stylus. However, the device is forced to switch between methods and thereby work at a vastly degraded position report rate. An additional disadvantage of Grenians is the usage of a pick-up stylus, which acts as a receiver and therefore has to be either connected to the host system by wire or alternatively must use an internal battery and transmitter. Both pick-up arrangements are undesirable for mobile systems.
U.S. Pat. No. 5,231,381 to Duwaer describes a combination of two independent sensors, one being sensitive to finger touch and the other being sensitive to stylus position, both incorporated in the same device. Duwaer""s device is capable of detecting finger touch and stylus simultaneously. However, the usage of two independent input sensors is a major disadvantage since it usually raises the price of the device. Furthermore, Duwaer""s device cannot detect multi finger touch and is therefore unable to support chord-key functionality.
In U.S. patent application Ser. No. 09/628,334 xe2x80x9cPhysical Object Location Apparatus and Method and a Platform using the samexe2x80x9d, to Perski et al, an electromagnetic pointing device using a transparent conductive overlay foil is described. The device is capable of detecting the location and identity of physical objects, such as a stylus, located on top of a display. The above electromagnetic technology enables the accurate position detection of one or more electromagnetic pointers, as well as sensing of multiple physical objects, for example playing pieces for use in games. However, the electromagnetic technology is inherently unable to sense a finger touch input, and is therefore inadequate for finger-based operation of an xe2x80x9con-screenxe2x80x9d or virtual keyboard. The above-mentioned application is hereby incorporated herein by reference and the reader is referred thereto wherein a method that allows simultaneous detection of different styluses or playing pieces at different positions is described.
In general, finger and stylus interactions require different detection techniques with different resolutions and different update levels. An attempt to use a single detection technique for both finger and stylus interactions is described in U.S. Pat. No. 5,543,589, to Buchana et al, which uses a four layer-two system transparent foil arrangement. Both systems use the same touch detection method but have different resolution levels and update rates so that one can sense stylus type interactions and the other can sense finger touch type interactions. A disadvantage of the system is the higher price of using two sensing systems and that the use of four foil layers markedly reduces visibility of the underlying screen when used over a display. An additional disadvantage of Buchana""s system follows from the use of two similar sensing systems. Full mouse emulation, as an example, requires the tracking of the stylus position while hovering above the display. Such a feature cannot be supported by a pressure sensitive system, which is on the other hand essential for finger touch detection.
There is thus a widely recognized need for, and it would be highly advantageous to have, a digitizer devoid of the above limitations.
According to one aspect of the present invention there is provided apparatus for user input to a digital system, comprising a first sensing system having first sensors for sensing a user interaction using a sensing method of a first type, and a second sensing system having second sensors for sensing a user interaction using a sensing method of a second type, said first and second sensors being co-located on a sensing surface.
Preferably, said first and said second sensing systems respectively are operable to sense simultaneously.
Preferably, said sensing surface is superimposed on a display screen.
Preferably, said sensing surface is superimposed on a part of said display screen.
Preferably, a first of said sensing systems is superimposed on a part of said display screen, and a second of said sensing systems is superimposed substantially over an entirety of said display screen.
Preferably, each one of said sensing systems is superimposed on a respectively independently defined part of said display screen.
Preferably, said first sensing system is a touch pressure-sensing system.
Preferably, said second sensing system is an electromagnetic based sensing system.
Preferably, said display screen is a flat panel screen.
Preferably, at least one of said sensing systems comprises sensor reading operability for reading multiple simultaneous interactions with respective sensors.
Preferably, said display screen is an LCD screen
The apparatus preferably comprises a connectivity interface for allowing fitting as an accessory to a computing system.
Preferably, said display screen is an electronic pad-type surface.
Preferably, said co-located sensing systems are constructed as a foil-based sensing arrangement.
Preferably, said foil-based sensing arrangement comprises at least one transparent foil.
Preferably, at least some of said sensors comprise organic conductive material.
Preferably, said transparent foil is a patterned transparent foil.
Preferably, said pattern is etched onto said foil, thereby to form said sensors.
Preferably, said pattern is printed on said foil, thereby to form said sensors.
Preferably, said pattern is introduced by passivation.
Preferably, said foil-based sensing arrangement comprises at least two superimposed transparent foils.
Preferably, sensors of said first sensing system are embedded in each of said at least two superimposed transparent foils.
Preferably, sensors of said second sensing system are embedded in each of said at least two superimposed transparent foils.
Preferably, sensors of said second sensing system are embedded in each of said at least two superimposed transparent foils.
Preferably, sensors of said first and said second sensing systems respectively are interleaved in said foil-based sensing arrangement.
Preferably, sensors of said first and said second sensing systems are interleaved in said first of said at least two superimposed transparent foils.
Preferably, said first and said second sensing systems have respectively different report rates for scanning respective sensors.
Preferably, said respectively different report rates are selected for compatibility with a respective one of said first and second user interaction type.
Preferably, said first and said second sensing systems have respectively different sensing resolution levels.
Preferably, said respectively different sensing resolution levels are selected for compatibility with a respective one of said first and second user interaction type.
Preferably, said first sensing system is an electromagnetic based sensing system, said respective user interaction is stylus operation and said respective resolution level is selected for compatibility with a respective application.
Preferably, said second sensing system is a pressure based sensing system, said respective user interaction is touch and said respective resolution level is selected for fingertip size.
Preferably, said foil-based sensing arrangement comprises two superimposed transparent foils, and wherein a first parallel arrangement of pressure-sensitive sensors is located on a first of said foils and a second parallel arrangement of pressure-sensitive sensors, orthogonal to said first parallel arrangement, is correspondingly located on a second of said foils.
Preferably, said superimposed foils are spaced apart by a flexible spacer to be pressed together upon application of pressure.
Preferably, said flexible spacer comprises a matrix of substantially non-conducting material with gaps, wherein said gaps are located to correspond to junctions between said first and second parallel arrangements of pressure-sensitive sensors, such that upon application of pressure at any given junction, corresponding sensors are brought into contact.
Preferably, said substantially non-conducting material is located to separate between sensors of said first sensing system.
Preferably, said flexible spacer comprises spacer dots, said spacer dots being concentrated about sensors of said first sensing system.
Preferably, said flexible spacer is printed onto at least one of said foils.
Preferably, each sensing system has a set of sensors located within said foil-based sensing arrangement, and wherein each set of sensors is arranged substantially as a grid.
Preferably, each sensing system has an arrangement of sensors set out to define detection co-ordinates and at least one of said sensing systems comprises scanning control functionality for scanning said detection co-ordinates in a multi-stage scanning operation, thereby to home in on multiple locations.
Preferably, said arrangement is a grid and said co-ordinates are Cartesian co-ordinates.
Preferably, said multi-stage scanning operation comprises a first stage of scanning groups of sensors along each axis of said grid, and a second stage of homing in on co-ordinates indicated in said first stage.
Preferably, said first stage comprises applying a sensing signal to all sensors of each group in a first axis, and reading each sensor in said second axis, and then applying a sensing signal to all sensors of each group in said second axis and reading each sensor in said first axis.
Preferably, said scanning control functionality is operable to determine whether an ambiguity is present, and, if an ambiguity is present to define suspect sensors as any sensor giving rise to a signal.
Preferably, said scanning control functionality is further operable to select each suspect sensor one at a time in a first of said axes, to apply a sensing signal thereto, and to read each suspect sensor in a second of said axes.
According to a second aspect of the present invention there is provided a pressure sensing apparatus for detection of at least two pressure locations, the apparatus comprising:
an arrangement of pressure sensors set out to define detection co-ordinates, and
scanning control functionality for scanning said detection co-ordinates in a multi-stage scanning operation, thereby to home in on said at least two pressure locations.
According to a third aspect of the present invention there is provided a sensor arrangement for superimposing over a visual display screen, comprising:
a first transparent foil having sensors of a first detection system for detecting a user interaction of a first type, and sensors of a second detection system for detecting a user interaction of a second type, embedded therein, and
a second transparent foil superimposed over said first transparent foil and flexibly spaced therefrom, having further sensors of said first detection system and of said second detection system embedded therein.
According to a further aspect of the present invention there is provided a pressure sensing arrangement for superimposing over a visual display screen, comprising:
a first transparent foil having a first set of parallel pressure sensors,
a second transparent foil, superimposed over said first transparent foil having a second set of parallel pressure sensors, said transparent foils being orientated such that said first and second sets of transparent foils are respectively orthogonal,
a substantially non-conductive spacer located between said first transparent foil and said second transparent foil to separate between said foils, said spacer being flexible to allow contact between pressure sensors on respective foils about a point of application of pressure, thereby to transfer a signal between contacted pressure sensors, and
a scanning controller for controlling a scanning operation to apply signals to said sensors and to read outputs in such a way as to provide unambiguous pressure information concerning every junction on a grid defined by said pressure sensors.
Preferably, said scanning operation comprises two stages, a first stage of scanning groups of sensors on each foil, and a second stage of homing in on junctions indicated in said first stage, thereby to detect simultaneous applications of pressure at multiple points.
Preferably, each scanning operation is an exhaustive scanning operation comprising individual testing of each junction.
Preferably, said first stage comprises outputting a signal to each sensor on one of said foils and detecting at each sensor on the other of said foils, then outputting a signal to each sensor on said other foil and detecting at each sensor on said one of said foils.
Preferably, said second stage comprises outputting a signal to each sensor, on one of said foils, that has been indicated in said first stage, and detecting at each sensor that has been indicated in said first stage on the other of said foils.
Preferably, said scanning controller is operable to carry out each of said two stages at substantially twice the frequency of fastest likely changes in a pressure application pattern.
According to a fourth aspect of the present invention there is provided a method of sensing of a plurality of pressure sensitive points arranged in a grid for detection of simultaneous applications of pressure at a plurality of said points, the method comprising testing said grid such as to obtain an unambiguous pressure detection result for each of said pressure points in said grid.
Preferably, said testing comprises:
outputting a signal to each of a plurality of sensors on one axis of said grid,
detecting at each of a plurality of sensors on a second axis of said grid,
outputting a signal to each of said plurality of sensors on said second axis of said grid,
detecting at each of said plurality of sensors on said first axis of said grid,
from said detecting deducing sensors that are possible sources of ambiguity, and
conducting further outputting and detecting to resolve said ambiguity.
Preferably, said conducting further outputting comprises selecting one of said axes and outputting a signal to each of said possible sources of ambiguity thereon, and said detection comprises detecting at each of said possible sources on the other of said axes for each said outputting.
Preferably, said testing comprises an exhaustive test of each of said pressure points individually.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The materials, methods, and examples provided herein are illustrative only and not intended to be limiting.
Implementation of the method and system of the present invention involves performing or completing selected tasks or steps manually, automatically, or a combination thereof. Moreover, according to actual instrumentation and equipment of preferred embodiments of the method and system of the present invention, whilst part of the invention requires hardware, certain selected steps may be implemented by hardware or by software on any operating system or any firmware or a combination thereof. For example, as hardware, selected steps of the invention may be implemented as a chip or a circuit. As software, selected steps of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In any case, selected steps of the method and system of the invention could be described as being performed by a data processor, such as a computing platform for executing a plurality of instructions.